How do changes in the mean occupied channel width and channel depth of the River Lyn compare with the Bradshaw model?

Consolidate your thinking – fieldwork to calculate
changes in the mean occupied channel width and depth of the River Lyn

The Bradshaw model states that both mean occupied channel
width(distance across a river
channel measured at the surface water i.e. not the wetted
perimeter) and mean channel depth
(height from water surface to the stream or river bed) will increase with
distance from the source to the mouth of a river. In both cases this will happen as additional
water volume (discharge input) is contributed from tributary streams and rivers
as well as surface runoff from a larger land catchment area as a river
progresses downstream.

To test this assumption against the real world example of
the River Lyn measurements can be taken of its occupied channel width and depth
at sample points along the course of the river and then tested statistically to
ascertain whether the changes identified are significant.

The film and narration on this pageshows clearly how to
measure the width and depth of a river and further guidance is available at

The width and depth of a river needs to be measured through
systematic sampling e.g. at every 10 m interval and the following sites along
the river are suggested as possible locations to take the sets of measurements
required:

Assessing risk and
identifying control measures to manage risk

Please refer back to guidance on this page and use the
template with regard to fieldwork above.

Secondary data sets

If access to these locations is not possible for primary
data collection then the following tables provide sets of secondary data
obtained from the sites for the students to test statistically: